The aims of the proposd work are to investigate the roles of covalent enzyme phosphorylation of hepatic lipogenesis and the activity of the key rate-limiting enzyme of fatty acid synthesis, acetyl-CoA carboxylase. Particular emphasis is being placed on the characterization of site-specific phosphorylation changes in the enzyme indued by hormones in the intact cell and the characterization in vitro of the major site-specific protein kinases and phosphatases responsible for these alterations. In addition, the regulation of hepatic lipogenesis by insulin is being employed as a model system for the further elucidation of the molecular mechanism of insulin action..